<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
		<body>
	<script>
		var str=prompt("请输入：例如'66688'格式")
			function  sandaiyi(str)
			{if(str.length!=5){
				return false;
			}else if(str[0]==str[1]&&str[1]==str[2]&&str[3]==str[4]
			){
				return ture;
				
		}
			return false;
			}
			alert(sandaiyi(str));
</script>
	</body>
</html>
